1. Field of the Invention
This invention relates to synthetic organic fibers that contain finely divided, abrasive, inorganic particles and a process for dispersing the particles in the fibers. More particularly, the invention concerns an improvement in such fibers, wherein the inorganic particles have a surface coating of an organic polymer, which is different from the polymer of the fibers. As a result of the improvement, abrasive wear of equipment used to handle the fibers is significantly decreased.
2. Description of the Prior Art
Synthetic organic fibers typically contain finely divided inorganic particles. The particles typically are intended to serve as delustrants, pigments, fillers, stabilizers, etc. The particles can be incorporated into the fibers alone or in combination with other materials and additives. For example, Anton et al, U.S. Pat. No. 5,108,684, which concerns the production of stain-resistant nylon fibers, discloses the use of a multipolymer nylon resin, in combination with the inorganic particles and other additives, to form a "master-batch" for incorporation into a nylon polymer that is melt-spun into fiber. Perrot et al, U.S. Pat. No. 4,710,535, which also concerns production of master batches for nylon fibers, discloses the combination of (a) 10-50 weight % of freely divided titanium dioxide particles coated with silica and alumina and treated with a polysiloxane oil, with (b) 50-90% of a nylon-6/66 copolyamide binder.
Fibers containing inorganic particles can be very abrasive and cause excessive wear in surfaces of equipment that come into contact with the fibers. The rubbing of moving fibers, filaments, threads and yarns which contain inorganic particles can severely abrade and score the surfaces of guides, rolls, winders, knitting needles and like equipment. To decrease such abrasive wear, various methods have been suggested. For example, lubricants have been dispersed into the body of the fibers or applied to the surface of the fibers to reduce fiber abrasiveness. However, further improvements are desired.
The present inventors in their attempts to decrease fiber abrasiveness found that unexpectedly large reductions in the abrasiveness of fibers can be obtained if the inorganic particles have a thin surface coating of an organic polymer when they are incorporated into the fiber.
Polymer-coated inorganic particles, per se, are known. For example, Published German Patent Application 4,317,019, discloses for use in paints, inks, plastics and cosmetic preparations, inorganic pigments which are coated with various organic polymers, such as melamine resins, polyethylene, polypropylene, polyurethanes, polyesters and others. Also, Ferrigno, U.S. Pat. No. 3,024,209, discloses the use of inorganic pigments coated with a polymeric film as fillers for extending flexible and semi-rigid open-celled polyurethane plastics. Neither of these references disclose the use of such coated particles in fibers.